With their new album i think the possibility is there for these guys to one day take over the top stop, once U2 call it quits. Coldplay is another band who could do it, and id like to think Muse, but i dont think i want them to turn mainstream in order to achieve it.
i don't think The Killers could do it. I love em', they're a favourite band of mine, but their music isn't widespread enough and they're a very niche band. Their music doesn't really speak for a whole lot of people. Truthfully I don't think any musical act is going to have a legacy like the old bands do anymore. I think the industry has changed, new music is always coming out because it's easier to distribute via the internet, and people are always looking for the next big viral thing.
If any band was to do it I'd say it's Coldplay. Muse is too inconsistent with quality of their material as they evolve as a band, but Coldplay have the ear of so many and their music (in my opinion) is getting bigger and bigger. But even Chris Martin said, Mylo was their 5th album and JT was U2's 5th album. Do they equate in quality and reception? Hell no.
Plus, The Killers are actually quite young. They've only got 4 studio albums. I consider Battle Born to be their "Joshua Tree." It's a very clean album and a very strong one as well. But when looking at their tour history, The Killers aren't big enough to fill stadiums yet, I feel. Or maybe this could be the tour in which they give stadiums a shot. I read an article a while back comparing The Killers and their tour to Muse and their tour. After assessing all the points, The Killers came on top. Now this, I agree with, because I do believe The Killers have a stronger stage presence than Muse.
But as said before, if any band were to surpass U2, it's going to be Coldplay. However, that trajectory is severely compromised with them cancelling their South American leg, imo. It appears that Coldplay doesn't have the same touring passion as U2 or they aren't able to sustain that energy for the same amount of time as them. Either way, it is a setback because you've got a lot of South American fans that are now disappointed.